Are camera speedlights universal?
In today's world flash units are as proprietary as lenses. This is due to what's called TTL and is really a misnomer for "Off Film/Sensor Flash Metering". Minolta patented TTL back in 1980 and its first application was in the Minolta CLE which was the result of a partnership with Leica. Its next appearance was in the Minolta X-700 which had a line of TTL dedicated flash units such as the 360PX and Auto Macro 80PX. With an X-700 in Auto Mode (Aperture Preferred) and a 360PX in TTL Mode the flash set the flash sync shutter speed and the camera controlled the flash duration based on the f-stop chosen. So I could confidently use an ISO 160 film and either f5.6 or f11 and bounce off a 12' white ceiling with perfect results. The same is true of today's DSLR's with TTL and a TTL-dedicated flash. However, if you are willing to give up TTL, there are flash units that can be used with various DSLR cameras. An excellent choice would be the Vivitar 285HV*. This flash features a Bounce Head as well as a Zoom Head (but no swivel head), has a Guide Number of 120, has 4 Auto f-stops (f2, f4, f8 & f11), has Variable Power (1/1, 1/2, 1/4, 1/16) and most importantly a Trigger Voltage of ~6V which makes it safe to use on your DSLR. Its fairly simple to use: just set the correct flash sync shutter speed on your camera and then 1) Set the ISO you're using on the flash and 2) Choose an f-stop based on the distance you're shooting from by looking at the dial on the side of the flash and set that f-stop on your lens. No TTL compatibility but an excellent flash for less than $100.00 brand new. Add the Wide-Angle panel and your coverage is from 28mm to 105mm. Since the unit doesn't have a swivel head you'll probably want to buy a flash bracket that allows the flash to swivel so you can use bounce flash in portrait orientation. Vivitar offered one and still may. Its a left hand grip but quite comfortable to use. You can occasionally find them on eBay. * If the flash doesn't say "285HV" DO NOT USE it on your DSLR. The older versions have a very high trigger voltage and may fry the electronics of your DSLR.
Is It possible to reduce the speed of light?
Yes it is possible and scientists have already slowed light quite effectively. It's the medium's permittivity on which speed depends on.If you say slowing the light in vacume then may be it is not possible till we can't find a way to manipulate space frequently. but if we choose a denser medium then light will slow up to a great extent.Explaining in details:See lights as a beam of photon particles . When a photon particles enters into a medium,the atom of the medium absorbs some energy and after fraction of seconds release it. this transmission of energy between photon particles and atom of the medium consume some time and the process continues till the photon particles is in side the medium resulting slowing down of light.In labs scientists successful slowed light upto 17 miles/hr..Using some other technologies (not medium dependent) they have successfully done it.Here some links where you can find more details about ithttp://www.physicscentral.com/ex...http://lofi.phys.org/news/2015-0...http://news.harvard.edu/gazette/...
What travels faster; the speed of sound or the speed of light?
I have a sneaking suspicion that the answer is somewhat obvious - to most, but it's interesting to compare the two, nonetheless. It's really no contest at all. Light travels at a speed of 186,000 MILES per second. (That's miles per second!)The speed of sound is dependent on what it's traveling through. In dry air at 68 degrees Fahrenheit, the speed of sound is 1,126 FEET per second.However, sound travels faster in liquids and non-porous solids than it does in air. Through water, for example, the speed is 4.3 times faster. Still, no matter what the condition by which sound travels, it's mightily slower than its counterpart - light.
Which speed light should I buy for my Nikon D3300?
First, determine what kind of photos you think you would need a flash for, then choose a flash to suit. Most likely, you might be the ‘free’ official photographer at gatherings, so there should really be no large group photos that would require a large expensive flash. You can choose a flash that is better than the flash that came with the camera, but not expensive. Learn what works with this flash to still give a natural look, before trying to upgrade. Too close or too far and you will not solve all the image problems you may encounter.Take shots at different distances for the same subject matter, so that you can choose after the fact.If you want a middle ground, choose one with wireless capabilities, so that you can place the flash away from the camera that can work in conjunction with the camera’s existing flash. This will also cater for a second flash in the future to increase the capabilities of your setup down the road, if you catch the bug.Remember, a badly composed shot will not be improved with the use of a flash.
Would you choose the SONY a6300 or a7?
let's say you dont care about videos. just photo. I see the a6300 with lens is about $1300. and the a7 with lens is about $1400. Let's say this is your first camera.
What speedlight would you recommend me to buy for my Nikon D3300?
Using the built-in flash leads to mediocre results because you cannot bounce the flash off a reflector and direct flash leads to a very unattractive "zombi white face" look along with a harsh shadow behind your subject.I have the Nikon SB600 and I like it a lot. It has been replaced by the Nikon SB700, but you probably don't need it since you aren't employing a multi-flash setup with the Nikon Creative Lighting System. I've heard a lot of good things about the Yongnuo flashes at a third of the price of the Nikon flashYongnuo YN-568EX Speedlite for Nikon Cameras Also... I know it says "macro" on that Tamron 18-200mm, but it isn't really a macro lens. It actually isn't the greatest of lenses for photographing people either (I owned a Tamron 18-200 myself a long time ago), I recommend switching it for the Tamron 17-50mm F2.8 (which I owned) or the Sigma 17-50 F2.8 which is supposedly better an on sale right now for only $400 (Sigma 17-50mm f/2.8 EX DC OS HSM Zoom Lens for Nikon 583306 B&H ). Sigma makes a 17-70 f2.8-4 macro for $400 USD as well, but I don't know how good it is (Sigma 17-70mm f/2.8-4 DC Macro OS HSM Lens for Nikon ).Hope this helps.
How did Einstein conclude that the speed of light is constant?
Often Einstein's Relativity Principle and the Light Postulate are quoted separately, so they look like this:1) Principle of Relativity: all laws of physics are form invariant in all inertial frames of reference.2) Light Postulate: the speed of light is constant in all inertial frames of reference.And quoted like this, it looks as though the light postulate is a bit ad hoc, and your question is a good one: why choose light?But in fact, if you look at 1 carefully, you can derive 2. You do it as follows: 1 can be restated as: all laws of physics are invariant in form in all inertial frames of reference including Maxwell's laws of electromagnetism.Maxwell's equations are unique in classical physics in having a fundamental speed baked into them. For comparison, note that Newton's laws talk about acceleration, not speed.More exactly, Maxwell has two constants: an electrical permittivity [math]\epsilon_0[/math] and permeability [math]\mu_0[/math]. Then, when you use the equations to derive a wave equation for the electromagnetic field, it spits out a wave speed of [math]c = \sqrt{\frac{1}{\mu_0 \epsilon_0}}[/math].But if Maxwell's equations are admitted as valid in all inertial frames, then so is this speed c. So the light postulate can be derived.Then the rest of the theory follows from here. (NB: for connoisseurs, you also need an additional assumption about the isotropy of space to derive the standard Lorentz transformations. This is often ignored, but given the later implications of GR, it is helpful to make it explicit).